Try This: The skull crusher, for toned triceps

If you don't want your upper arms waving long after you've said goodbye, you'll need to work on your triceps.

The supine triceps extension, sometimes called the skull crusher, is one of the simplest yet most powerful ways to sculpt this muscle. The move, demonstrated here by celebrity trainer Harley Pasternak is featured on his "Harley's Hollywood Workout" video game.

What it does

This exercise tones your triceps — the biggest muscle in your arms — making them look longer and leaner.

What to do

Lie down on a mat with your back flat against the floor, knees bent, with the soles of the feet touching the floor.

With or without light hand weights, extend your arms straight up to the ceiling in line with your shoulders. Slowly bend your forearms back from the elbow behind your ears. Then raise them back to the starting position, keeping your lower back pressed into the floor and elbows pointing straight up.